Using LTVT with Mars Photos
Examples..
As an example of Changing the target planet and Saving/Changing the *.ini file, this page explains how to set up LTVT for use with photos of Mars.
Since the options applicable to displaying and analyzing photos of Mars are quite different from those applicable to the Moon it is helpful to have a Mars.ini file to which your Mars preferences can be saved and from which they can be restored.
1. First go to the Map-a-Planet website and download texture files for Mars in simple cylindrical projection spanning the longitude range -180° (west) to +180° (east) and the latitude range +90 to -90°. Resolutions of 16 or 32 pixels per degree are more than adequate for comparison to amateur images of this small planet. The MOLA topographic grayscale image, MGS-MOC W-A Mosaic of surface images, Magellan Color image and MGS TES Albedo are all useful.
2. Verify that the downloaded textures are displaying "planetocentric" (as opposed to "planetographic") latitudes (latitudes on a sphere rather than referenced to a flattened ellipsoid). The distinction can be seen by loading them as textures into LTVT (which assumes the latitudes are planetocentric) and comparing the LTVT-drawn latitude lines with those shown on an official IAU map marked in the two systems. The MOLA regional (PDF) map is an example of one of these. For example, at 50°S there are craters at 246.5 and 251.5°E longitude. The top of the first is tangent to the 50°S line in the planetographic system, while the top of the second is tangent to the same line in the planetocentric system.
3. Download and save to your LTVT folder the Mars IAU names dot file from the present website
4. Open LTVT and in the Tools menu choose Change target planet... and set it to Mars.
5. In the File Associations Menu:
- a. In the "Textures" panel, change the three textures to your preference of ones downloaded from Map-a-Planet, adding descriptive titles for display next to the radio buttons. If the latitudes in any of the texture maps are planetographic (causing features to display at the wrong latitudes -- see Item 2, above), this should be corrected by marking the appropriate check boxes.
- b. In the "Other External Files" panel, change:
- i. Dots/Names: point to the downloaded Mars IAU names file.
- ii. Calibrated photos: invent a new name for calibrated Mars photos, such as "MarsPhotoCalibrationData.txt". The first time you try to save data to this file, LTVT will complain that it does not exist. When you see this message, pick the option that says "choosing no will create a new one" and a file of that name will be created containing the data for your first calibrated Mars photo.
6. In the Mouse Options window, set the "Longitude display convention" to -360 to 0° if you would like to display west longitudes, as is traditional with most Mars observers (or one of the other systems if you prefer).
7. Click the Now or Compute geometry button and verify that the display is as you wish.
8. In the Files menu select Save all options... and when asked for the name of the file you want to save the options to, choose something like "Mars.ini".
9. At any later time, the options set above can be restored by choosing Change *.ini file... from the Files menu.
This page has been edited 2 times. The last modification was made by - 
JimMosher on Mar 22, 2010 8:06 pm